docs: def _extract_coeffs(self, imt):
          """
          Extract dictionaries of coefficients specific to required
          intensity measure type.
          """
          C_HR = self.COEFFS_HARD_ROCK[imt]
          C_BC = self.COEFFS_BC[imt]
          C_SR = self.COEFFS_SOIL_RESPONSE[imt]
          SC = self.COEFFS_STRESS[imt]
  
          return C_HR, C_BC, C_SR, SC